Hi
I filed my i140 with USICS and got an RFE that is asking for :"USICS received evidence of Beneficiary employment ; however X and Y cannot be the source of Beneficiary experience. They may be source of the skills they acquired throughout the years. Therefore please submit evidence that the beneficiary gained the required experience prior to Nov 2015. Evidence of experience must be in the form of letters from current or former employers giving the name, address, and title of the employer and a description of the experience of the alien including specific dates of employment and specific duties.Evidence can be following :
Paystubs
Letters from HR
Letters from management"

I submitted letters from my colleague during the i140 and the letters seems to be rejected.
My previous will not give me any letter as left them in US.

I do have all the paystubs till date , but not sure how will it help uSICS with description of the experience.